Ligaments are strong bands of fibrous tissue that can connect bones, such as the bones of the spinal column. There are two primary ligament systems in the spine, the intrasegmental system and the intersegmental system. The intrasegmental system holds the individual vertebrae together, and includes the ligamentum flavum, interspinous and intertransverse ligaments. The intersegmental system extends along the length of the vertebral column, and includes the anterior and posterior longitudinal ligaments, and the supraspinous ligaments.
Both of these ligament systems work in conjunction with the facet joints to provide structural stability and/or prevent excessive movement of the spinal column. Particularly, the ligamentous structures exhibit a non-linear relationship between motion and force, where initially little force is required for motion, and a greater additional force is required at larger motion. Further, these structures have properties that allow them to stretch a large amount before breaking.
Diseased, degenerated, impaired, or otherwise painful ligaments can require surgery to restore their function. While current artificial ligaments may relieve pain, they typically provide less motion than natural ligaments. Furthermore, many artificial joint replacements, such as spine, knee, hip, and shoulder, require extensive removal of the ligaments surrounding the joint. The functions of the ligaments removed should be restored to stability of the joint.
Accordingly, there remains a need for improved systems and methods to replace the ligaments of human body, and in particular, the spine.